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Air noise after RT shock service - Rebound Separator Valve Install


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Hey guys,

 

2014 KTM350sx-f, sent my suspension in to Race Tech for complete kit. Part of the service included installing their Rebound Separator Valve (http://www.racetech.com/EmailList/News/RTnews-080430.html). I didn't notice this air noise right away but now that I have it's been stuck on my mind. With the wheels on the ground, when I push down on the seat to compress the shock I can hear air escaping and then sucking back in when it rebounds. Can anyone else confirm that this is normal? It makes sense now that I have researched some and called RT about it, but I've never experienced this with any other bike. The travel seems to be smooth except for the instant that it transitions from compression to rebound, you can feel the rebound kick in and slow down. 

 

I'm just looking for people with similar experience who can say if this is normal or not.

 

Here's a little video with swingarm POV where you can see the suspension working.

https://www.youtube.com/watch?v=kt45QMlPQjo

 

Thanks!

 

-Steve

Edited by Bmx360Biker
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If it's indeed the shock making this noise and not the mudflap or some other component then no the shock should not be making any such noise. What's strange to me is how you pointed out how the shock reacts when pushing on the seat. Does the rear of the bike act unusual (kicking and/or very harsh) when riding also? 

Edited by DDEsuspension
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Sometimes what you hear on the rebound stroke is just the oil moving through the port. Totally normal makes a hiss noise or sucking noise. If it was air escaping the shock would be dead, basically very pogo stick like because it would only be a spring. Since there would be no pressure for the oil to flow

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The travel seems to be smooth except for the instant that it transitions from compression to rebound, you can feel the rebound kick in and slow down.

 

It feels like the moment you switch from compression to rebound there is a lapse in dampening. Then you can feel it dampen the rebound after about 2cm of travel which is why I don't really notice it on the track. I wonder if there is an air bubble (RT assured me their fancy machines don't do air bubbles), either way, RT has offered to check it out free of charge if I ship it to them. Time for winter tear down again.

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  • 2 weeks later...

RT assured me their fancy machines don't do air bubbles.

Anything is possible. Like some unwanted air is in the oil, which sits around the compression adjuster valve. Or they forgot to gas pressurize the shock, so it foams up almost immediately.
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